Recently, FM receivers which are adapted for receiving not only usual FM broadcasting signals, but also TV broadcasting sound signals have been developed. Such an FM receiver usually is provided with an FM receiving band and a TV sound receiving band. The bands are selected by a band selector.
In a conventional multi-band FM receiver, however, the FM receiving band is assigned to receive the FM broadcasting signals and TV broadcasting sound signals of the lower frequency channels, i.e., the channels 1, 2 and 3. On the other hand, the TV sound receiving band is assigned to receive the TV broadcasting sound signals of the higher frequency channels, i.e., the channels 4, 5, ..., 12.
This is because the frequencies of the lower frequency TV channels are closer to the frequencies of the FM broadcasting signals than to the frequencies of the higher frequency TV channels. Under the circumstances, the multiband FM receiver can be designed easily by assigning the lower frequency TV channels to the FM receiving band, instead of the TV sound receiving band. Thus, the TV channels are separated into at least two receiving bands in the conventional multi-band FM receiver.
However, users of the conventional multi-band FM receiver must select the FM receiving band, when reception of the TV broadcasting sound signals of any the lower frequency channels is desired. Therefore, the conventional multi-band FM receiver has a drawback in that it confuses the users, due to the inconsistency between the use of the FM receiving band and the reception of the TV sound signals.
In addition, the FM broadcasting signals and the TV broadcasting sound signals are different in the degree of FM modulation. The degree of FM modulation of the TV broadcasting sound signals is less than that of the FM broadcasting signals. As a result, different sound levels are output from the FM receiver for the FM broadcasting signals and the TV broadcasting sound signals. Thus, a user must operate the volume control for adjusting the output sound level, when changing between the FM broadcasting signals and the TV broadcasting sound signals in the FM receiving band.